Ever grabbed a bag of chips or a frozen meal for a quick bite? You're not alone, ultra-processed foods (UPFs) make up a huge part of our diet, especially in the industrialized countries where life is often fast moving and hectic, UPF provides instant energy in a very tasty, cheap and fast format. But beneath their convenience lies a potential threat to your gut health which can in turn affect other systemic pathways  in the body and a disruption to the gut microbiome. In this blog, we'll explore how UPFs affect the gut microbiome, health and the mitigating steps to be taken , drawing from supporting scientific studies. 

What Are Ultra-Processed Foods?

UPFs are industrially made food products loaded with additives like emulsifiers, sweeteners, and preservatives. According to the NOVA classification system (a classification system mostly used by nutritionists and clinicians), UPF’s are the 4th group and consist of all foods high in sugars, unhealthy fats, and synthetic ingredients. Sodas, packaged snacks, processed meats, and ready-to-eat meals belong to this group. These types of food are usually high in energy density and palatable but low in micro and macro nutrients like fibre, vitamins and minerals. They dominant diets in many countries, thanks to their long shelf life and affordability.

Food processing, especially at high temperatures used in the manufacturing of UPFs like fried potatoes, biscuits and bread  can lead to the production of toxic substances which are harmful along with the food additives like taste enhancers, coloring agents and emulsifiers. High temperatures during processing may also lead to changes in the composition of the food, further lowering its nutritional value and production of carcinogenic substances like acrylamide, heterocyclic amines, and polycyclic aromatic hydrocarbons as a result of complex chemical reactions which disrupt cellular pathways causing diseases like cancer.

Figure 1: NOVA classification of food based on the level of processing done

Gut Microbiome: The Unsung Hero

Your gut is home to trillions of microbes: bacteria, fungi, and more that form the microbiome. This ecosystem aids digestion, boosts immunity, and even influences mood via the gut-brain axis. Key players include beneficial bacteria like Akkermansia muciniphila and Faecalibacterium prausnitzii, which produce short-chain fatty acids (SCFAs) important for gut-barrier integrity and gut health. Diversity is key; a balanced microbiome protects against pathogens and inflammation. Modern habits, like consumption of UPFs, can throw this balance off, leading to dysbiosis, a shift toward harmful bacteria that might induce inflammation and further compromise the gut-barrier integrity of the host organism (that is you!).

How UPFs Wreak Havoc on Your Gut

UPFs disrupt the microbiome in sneaky ways. Their low fibre content starves beneficial bacteria, while additives like emulsifiers (e.g., carboxymethylcellulose) promote pro-inflammatory microbes. Studies show UPFs reduce microbial diversity and boost pathogens, increasing gut permeability or "leaky gut" caused due to weakened gut barriers making it easier for pathogens to enter and exit the gut without any checks. For instance, a study found that emulsifiers altered microbiota, reducing SCFAs and causing inflammation. High saturated fats in UPFs also favour harmful bacteria over the beneficial ones. In short, UPFs create an environment where bad bacteria thrive, compromises the gut's protective mucus layer and allowing toxins to leak into the bloodstream.

Figure 2: Visual representation of leaky gut pathway caused by UPF and lack of diversity of microbes

The Health Ripple Effects

The effects of UPF’s are not just confined to gut health; it fuels chronic issues. Dysbiosis from UPFs is tied to metabolic syndrome, type 2 diabetes, and cardiovascular disease. A 2023 study associated high intake of UPF with the risk of colorectal cancer, possibly due to microbiome changes. The UPF’s induced dysbiosis might also interfere with the usual gut- brain communication, contributing to depression and cognitive decline. Untimely consumption of large quantities of UPF’s might interfere with the sleeping patterns and can also disrupt circadian rhythms.

Fighting Back: Dietary Strategies to Rebalance Your Gut

Good news! You can counteract UPFs with smart choices. Reduce UPF intake and focus on whole foods: fruits, veggies, whole grains, and lean proteins boost microbial diversity . Amp up fibre legumes, nuts, and seeds feed good bacteria, producing SCFAs for barrier repair. Fermented foods like yogurt, kefir, kimchi, and sauerkraut deliver probiotics naturally. A 2021 study showed, fermented foods increase microbial diversity and reduce inflammation. Probiotic supplements (e.g., Lactobacillus or Bifidobacterium) and prebiotics (like inulin) can help to restore the lost gut microbial balance . Lifestyle tweaks matter too, exercise enhances diversity, while stress management and good sleep support gut health.

Wrapping Up: Choose Wisely for a Healthier Gut

UPFs might be convenient, but their impact on your gut microbiome lowering diversity, sparking inflammation, and raising disease risk is clear from various recent scientific literature . By swapping UPF with fibre-rich, fermented foods or adequate consumption of these with lower intake of UPF can help to mitigate the risks caused by UPF. By adopting healthy eating habits, you can nurture your gut's ecosystem. Small changes add up to a better health and your microbes will thank you.

-Aravind Krishna

References

Monteiro, C. A., Cannon, G., Moubarac, J. C., Levy, R. B., Louzada, M. L., & Jaime, P. C. (2018). The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutrition, 21(1), 5–17. https://doi.org/10.1017/S1368980017000234

Cordova, R., Viallon, V., Fontvieille, E., Peruchet-Noray, L., Jansana, A., Wagner, K. H., ... & Tjønneland, A. (2023). Consumption of ultra-processed foods and risk of multimorbidity of cancer and cardiometabolic diseases: A multinational cohort study. Lancet Regional Health - Europe, 35, 100771. https://doi.org/10.1016/j.lanepe.2023.100771

Raoul, P., Cintoni, M., Palombaro, M., Basso, L., Rinninella, E., Gasbarrini, A., & Mele, M. C. (2022). Food Additives, a Key Environmental Factor in the Development of IBD through Gut Dysbiosis. Microorganisms, 10(1), 167. https://doi.org/10.3390/microorganisms10010167

Chassaing, B., Compher, C., Bonhomme, B., Liu, Q., Tian, Y., Walters, W., ... Gershuni, V. (2022). Randomized Controlled-Feeding Study of Dietary Emulsifier Carboxymethylcellulose Reveals Detrimental Impacts on the Gut Microbiota and Metabolome. Gastroenterology, 162(3), 743–756. https://doi.org/10.1053/j.gastro.2021.10.028

Daniel, N., Gewirtz, A. T., & Chassaing, B. (2023). Akkermansia muciniphila counteracts the deleterious effects of dietary emulsifiers on microbiota and host metabolism. Gut, 72(5), 906–917. https://doi.org/10.1136/gutjnl-2021-326835

Fiolet, T., Srour, B., Sellem, L., Kesse-Guyot, E., Allès, B., Méjean, C., ... & Touvier, M. (2018). Consumption of ultra-processed foods and cancer risk: Results from NutriNet-Santé prospective cohort. BMJ, 360, k322. https://doi.org/10.1136/bmj.k322

Monteiro, C. A., Cannon, G., Levy, R. B., Moubarac, J. C., Louzada, M. L., Rauber, F., ... & Cediel, G. (2019). Ultra-processed foods: What they are and how to identify them. Public Health Nutrition, 22(5), 936–941. https://doi.org/10.1017/S1368980018003762

Severino, A., Tohumcu, E., Tamai, L., Dargenio, P., Porcari, S., Rondinella, D., ... & Cammarota, G. (2024). The microbiome-driven impact of western diet in the development of noncommunicable chronic disorders. Best Practice & Research Clinical Gastroenterology, 72, 101923. https://doi.org/10.1016/j.bpg.2023.101923

Mazloomi, S. N., Talebi, S., Mehrabani, S., Bagheri, R., Ghavami, A., Zarpoosh, M., ... & Kermani, M. A. H. (2023). The association of ultra-processed food consumption with adult mental health disorders: A systematic review and dose-response meta-analysis of 260,385 participants. Nutritional Neuroscience, 26(5), 913–931. https://doi.org/10.1080/1028415X.2022.2086066

Depommier, C., Everard, A., Druart, C., Plovier, H., Van Hul, M., Vieira-Silva, S., ... & Cani, P. D. (2019). Supplementation with Akkermansia muciniphila in overweight and obese human volunteers: A proof-of-concept exploratory study. Nature Medicine, 25(7), 1096–1103. https://doi.org/10.1038/s41591-019-0495-2